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Label-Free Measurements of the Diffusivity of Molecules in Lipid Membranes

Björn Johansson (Institutionen för teknisk fysik, Biologisk fysik) ; Fredrik Höök (Institutionen för teknisk fysik, Biologisk fysik) ; D. Klenerman ; P. Jonsson
Chemphyschem (1439-4235). Vol. 15 (2014), 3, p. 486-491.
[Artikel, refereegranskad vetenskaplig]

An important and characteristic property of a cell membrane is the lateral mobility of protein molecules in the lipid bilayer. This has conventionally been measured by labeling the molecules with fluorescent markers and monitoring their mobility by different fluorescence-based techniques. However, adding the label to the studied molecule may affect the system, so it is an assumption in almost all experiments that the measured mobility of the biomolecule with its label is the same as that of the unlabeled molecule. However, this assumption is rarely tested due to a lack of suitable methods. In this work, a new technique to perform label-free diffusivity measurements is developed and used to measure the effect of the label for two common protein-lipid systems: 1) streptavidin (SA) coupled to a supported lipid bilayer (SLB) through biotinylated lipids and 2) the extracellular part of the T-cell adhesion protein CD2, coupled to an SLB through histidine tags to nickel-chelating lipids. A measurable (approximate to 12%) decrease in diffusivity is found for both labeled proteins, even though the molecular mass of the label is almost 100 times smaller than those of the proteins (approximate to 50 kDa). The results illustrate the importance of being able to study different biophysical properties of cell membranes and their mimics without relying on fluorescent labels, especially if fluorescent labeling is difficult or is expected to affect the nature of the intermolecular interactions being studied.

Denna post skapades 2014-04-08. Senast ändrad 2014-04-15.
CPL Pubid: 196413


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Institutionen för teknisk fysik, Biologisk fysik (2007-2015)



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